(Note: These planting guidelines are for consideration to iris growers in the east and Midwest only.)
THE BEST PLACE TO PLANT YOUR IRISES
Imagine that every tree in your yard is now fully mature. Look upward and make certain that no tree limbs are or will become closer than 10 feet from the edge of your planting area. Tree roots will extend from that tree an equal distance and your wonderful soil we eventually be ruined. Avoid shade as irises are sun lovers. Full sun make them the happiest!
Survey the lay of the land. Spot areas with higher elevation. Excellent drainage is an essential requirement of irises! Good soil grows lush weeds with large leaf surfaces and dark green grasses. Some gravel is not a bad thing as it improves drainage, but boulders are very bad. Clay soils are a godsend as they retain moisture and trap organic matter and fertilizers.. Sandy soils offer excellent drainage—a disaster in drought conditions.
Avoid slopes. Soils will wash against the foliage and bury the rhizomes—a deadly invitation to bacterial infections.
IMPROVING YOUR SOIL
Whatever soil you have on your property contains unknown qualities but you can bet it exists there for many good reasons. Quality soil amendments can be cultivated and fluffed into your native soil but too much of a good thing encourages erosion. Bury them underneath your native soil then recover. Your plants will get full use of the materials quickly and for a longer period of time.
Get a soil test before you begin to think about planting. The local farmers coop provides soil containers and will explain to you how to gather soil for their lab tests. Be sure to request recommendations to create a soil with a pH of 7.0 and that you are planting bearded irises.
Manures are a breeding ground for grubs that feed the tunneling moles (carnivores) whose tunnels provide an underground pathway for voles (herbivores) who eat iris plants and rhizomes. Rotting leaves are delicious and alfalfa products in small quantities are amazing and expensive!! I love manures but they have tons of weed seeds.
Chemical fertilizers should always be buried under your plants. Topical applications of potassium and phosphate scratched into the soil is time wasted as they are washed away with heavy rains. Nitrogen moves only vertically but pellets that wash against and onto your plants during rainfall may burn and damage plant tissues.
It is desirable to prepare your soil in the autumn prior to planting. Late summer/early autumn cover crops yield amazing results and can be “plowed under” before winter so that your planting areas can settle during the winter. I highly recommend mounding the soil 12” higher than ground level or create 12” planting ridges or mounds which will easily settle to 6” in height come spring.
Plant your irises on raised mounds or ridges. It is very important that you firm the soil under the rhizomes as you plant. In the south (before winter), check to be sure the top half of the rhizome's surface is above ground (crawdad style).
If you intend to leave the bed undisturbed for 3 years, plant your single rhizomes 36”apart. Quality varieties will produce perfectly happy clumps! Plant them closer and you will have an iris jungle!
Water heavily when planting—very heavily! In future watering, keep the foliage dry as possible. Drip tapes or soaker hoses will do the job!
WEEDING and MAINTENANCE
Care for your irises like you would your vegetable garden. Grass and weeds are never welcome. I suggest that you capture (kidnap) a skilled gardener who loves to weed, making certain that he/she is wealthy and generous. Spend some extra bucks to install security fences to prevent any possibility of escape!
Associate with friends who can provide access to an experienced hoe-er. Every beautiful garden has benefited from the services of a good hoe-er.
Never be without vinyl-coated fabric gloves. They protect from hand punctures, scrapes and broken fingernails.
Buy at least a half-dozen one gallon garden sprayers when they are on sale. Label each container with a permanent marker including the name of the chemical you are using, it specific purpose and exacting directions for mixing! Use this sprayer ONLY for this mixture.
Find two wide-brimmed straw hats in late winter and early spring before the good ones are sold! I can assure you that spring winds can blow that hat into another state. In the blink of an eye it may fly off your noggin and under your lawn mower It is an inexpensive way to avoid skin cancer and premature wrinkles around your eyes.
Mulching helps retain moisture in the soil and keep down unwanted vegetation. Make certain that you do not place mulch on top of the rhizomes!
Weeding is a science of order and discipline. When heavy rains appear anticipate a massive germination of weed and grass seeds. In order to keep your unwanted vegetation under control, you need a plan of attack! Select three categories of grass and weeds that need to be removed first.
Recognize and identify those that are the most persistent (the most difficult to destroy and keep in check), the most aggressive (grasses!), and the toughest to eliminate (those with tap roots, and creeping rhizomes). When making your first trip through the garden, get these evil demons first! You will finish round #1 with a sense of great accomplishment and the entire task won't seem so impossible! Round #2 go for the big ugly ones before they become too established to pull easily. Round #3 will leave the little oxalis and short-lived plants that will do the least harm to your iris plants. In many cases, these little fellas will already be yellowing and preparing for their disappearance!
DISEASES, PESTS and UNWELCOME GUESTS
I never remember a time that there were no moles in our yards. I have already mentioned that they are responsible for the destructive voles. I kill grubs. They are evil. You have read my spin above on the grubs/moles/voles. Discover Imidicloprid insecticide—first marketed as Merit. It must be applied here in the month of October in order to kill all those baby grubs! We do not have the iris borer in Tennessee, but Imidicloprid is also a great weapon to eradicate the iris borer that haunts gardens north of us.
Fire ants have finally made the journey north into Tennessee. They won't hurt an iris but they can bury a plant under a mounded sculpture of soil. I have destroyed mounds that had buried iris plants after the stinging villains have abandoned their hut, but the iris plants started growing immediately and bloomed the following spring. You can gently disturb a fire ant mound and they will break up housekeeping, reproduce and build other mounds (plural) nearby!
If grass is out of control, discover Sethoxydin contact herbicide. It is still available in pint containers marketed as Vantage contact herbicide. Young grass dies in days; older grasses may require re-application.
Broad-leaf weeds? Clopyralid contact herbicide (introduced under the name 'Stinger') is an effective option. Again...small plants die quickly. Overgrown weeds? I don't dare add more chemical to the sprayer! Summons your hoe-er!
Leaf spot or crown rot? Try chemical-free Consan Triple Action fungicide and algicide. It is chemical-free and is a detergent invented and first marketed to the restaurant industry to clean cutting surfaces, walls, floors and dirty vegetables.
Chant after me: “No chemicals! No chemicals!”
24-D brush killer? Don't you dare. It is a product of Satan.
PURCHASING NEW VARIETIES
When we are new to irises, all varieties seem wonderful. Sadly, there are multitudes of long-time iris devotees who never learn differently. Here are an even dozen tips to help you purchase quality iris plants for your garden.
-Avoid varieties over 36” tall. They are not wind-proof or rain-proof.
-Early bloomers are often victims of late freezes.
-Flowers with wide hafts and petals project more color in the garden.
-Stalks that open one bloom at a time remain in bloom three times longer than those that open 3 blooms at once!
-New introductions often have lengthy, flattering descriptions. If there is no mention of bud count, branching, haft width, vigor, etc., there is an excellent chance that the variety is lacking in these qualities.
-Parentage of a new variety is often a clue to a plant's behavior and habits.
-Some iris breeders exaggerate.
-Some iris breeders see no faults in their “children”. (A type of blindness??)
-A plant that is overly vigorous is as problematic in the garden as one that sulks.
-A plant that does not bloom each year is no bargain.
-A plant with erratic growth and/or disease susceptibility is trash.
-An iris that wins an American Iris Society award may not be a good garden iris.
Some years ago at an AIS convention during judges training, a debate ensued concerning inferior varieties winning major awards. Famous hybridizer, Ben Hager from Stockton, California asked to be recognized. His comments were brief:
“There are many irises that should be introduced, but AIS judges need to learn that only top quality introductions should be presented an award!”
Sadly, some very important things do not change.